Skip hoist motor control



Sept. 11, 1951 Filed March 18, 1949 SKIP CONTROL 5 Sheets-Sheet l Motor2 Motor 1 12 5 Fig.1

IKSA U 65M? GEN. am ZSERJLD. a

lsrmron flu RI u i I x.coMM. '21 L F117 X.6Z."R.FZ'D. E X 671 F ARI/0 IXm msw r'ixs nn.

. a 7 KS5 KS8 h f awflsaizo. 02w? SHJLD. h

I mew/mum I imk fi wm- TR? Match 5 181 INVENTOR. .9- zpartA Gordon FoxATTORNEYS,

Sept. 11, 1951 G. FOX 2,567,427

SKIP HOIST MOTOR CONTROL Filed March 18, 1949 3 Sheets-Sheet 2 Maia/2Line '3 filit Tki' RIGt TRH m m m KSH K51 Right Skip At Tqo L eft SkipAt71p Limi l Swi 1 ch FUSE 57D RESET IGL/ 4 M Skg'pAl Top 14 Left Skip AtLimil Switch Indie-a a Closed 1 N VEN TOR.

Conlaci Gordon Fox A TTORNEYJI Patented Sept. 11, 1951 SKIP HOIST MOTORCONTROL Gordon Fox, Chicago, Ill., assignor, by mesne assignments, toKoppers Company, Inc., a. corporation of Delaware Application March 18,1949, Serial No. 82,239

13 Claims.

The present invention relates to improvements in skip hoist motorcontrols.

United States Letters Patent 2,379,958, issued July 10, 1945, UnitedStates Letters Patent 2,370,855, issued May 10, 1945, and applicationfor United States Letters Patent Serial 618,015, filed September 22,1945, all in the name of the present applicant, disclose skip hoistmotor controls employing a pair of hoist motors for operating thewinding drum of a skip hoist. v

Said Patent 2,370,855 discloses-and claims a dual drive skip hoistprovided with an adjustable voltage control in which an adjustablevoltage generator supplies direct current to the two hoist motors, whichmay be connected either in series with each other or in parallel witheach other.

The arrangement disclosed in Figure 3. oft-he above Patent 2,370,855contemplates a generator large enough to supply both motors. When onemotor is required to operate alone, there'is an abundance ofgeneratorcapacity to supply said motor without installing an oversizegenerator as a part of the motor generator set. 'Inthe arrangementmentioned, if this single generator should fail, the hoist would beinoperative. In view of this fact, installations have been made .in'which two generators are employed, one supplying power for one hoistmotor, and the other generator supplying power for the otherhoistlmotori If a single one of said generators is utilized in anemergency to supply a single motor to operate the hoist, certaincomplications arise. Firstly, the dual-drive hoist must be driven by asingle motor,

rather than by two motors, there being some dis-I Secondly, the

advantages to such procedure. single operating generator must supplysufiicient' current to develop suincient torque in the single operatingmotor to handle the hoist with whatever load may be involved.Ordinarily, the loadinstalled normally have some reserve capacity forsingle motor operation. With a setup as just described, the generatormust have corresponding'oapacity and must therefore be oversize, that;is, it must be more than half as large as a single,

generator supplying two motors in parallel.

Expressed in other language, it has beensugn gested in the past tosupply the two motors of a dual skip hoist from two generators. In someinstances, each generator has been adapted to supply one motorseparately; In other instances,

the two motors and the two generators have been connected in staggeredseries. This means that the armatures have been connected in a circuitcomprising one generator followed by one motor followed by the othergenerator followed by the other motor, thence back to the point oforigin. If the generators are connected to supply their individualmotors only, the operation of a skip hoist is somewhat circumscribed inthe event of trouble with either motor or either generator. If themotors and generators are connected in staggered series, the arrangementis effective in the case of the loss of one generator as the remaininggenerator can be utilized to supply the remaining two motors. The samecurrent passes through both motors and causes them both to developtorque, retaining the dual drive feature of the hoist. Because of theloss of one generator, the voltage of the circuit is halved andconsequently the speed of operation is correspondingly reduced. Thestaggered series arrangement is not very satisfactory in case of theloss of one motor. In such event it becomes necessary to jumper out thearmatures of the other motor and its corresponding generator. The singleundamaged motor is then supplied from a single generator. The capacityof the hoist is approximately halved.

The mill-type motors commonly employed for skip hoist service haveconsiderable reserve capacity. By means of forced ventilation, it ispossible to utilize this capacity in single motor operation to an extentgreater than commonly applies in the case of dual drive. It is obviousthat if the inherent overload capacity of the motor is to be utilized inan emergency for single motor operation, a corresponding generatorcapacity must be available. The generators ordinarily used, however, donot have as much overload capacity as the mill-type motors. Therefore,if a single generator is to be used in such an emergency it must havemarginal capacity, that is,

is must be oversize.

An object of the present invention is to provide a skip hoist motorcontrol involving a pair of driving motors and a pair of generators forsupplying current to said motors which skip hoist motor control avoidsthe difficulties heretofore encountered in two motor, two generatorsystems as above discussed.

A further object is to provide a skip hoist motor control employing twodriving motors and two generators for supplying current to said motorsin which satisfactory emergency operations can be carried on in theevent of breakdown of either of said motors or either of saidgenerators.

parallel to supply the one motor, therebyinsur:

ing maximum torque of the motor.

A further object is to provide an improved skip hoist control employingtwo driving motors and two compound wound generators which -thecompounding field windings may be crossed when.

the two generators are operated in parallel and maybe connected inseries with their respective arm'atu'res when" eachgeneratorsupplies itsrespecti've motor and when" either generator "supplies the two motorsconnected in series. 7

' Further objects will appear as the description proceeds. Referring tothe drawings- Figure 1 is a plan View illustrating thewinding drum foroperating the two cables of a double skip hoist, such winding drumhaving associated there'-' with limit switch means, driving "motors,brakes and gearing for operating and "controlling said winding drum;''"1' i'Figur'e 2 is anelectri'ca'l diagram which, for'con; venience," isdivided into two parts indioatedas Figure 2, part A, and Figure 2; partB; 7 Figure 3. isa tabulation showing'the positionsof the severalswitches and circuit breakerswhen operating thezskipjhoist' motorcontrol in any of six possible combinations; and. i Figure 4 is atabulation'ofjthe control transfer switch positions for settingup thevarious com= binations'referred to in connection with Figure 3.

DESCRIPTION OF INSTRUMENTALITIES Asillustrated in Figure 1, a pair ofdriving motors land 2 is provided. Said motors- -|-and 2- areconnectedthrough couplings 3 and Arespectively, through brakes 5 and 6to gear ..I'C1-ll0= Letters BR refer to the operating coils and contactsresponsive thereto on the brake contactors.

Letters EX refer to the exciter of the motor generator set.

Letters KS refer to various knife switches.

Letters LSU refer to the operating coil and contacts, responsivethereto, of a relay, controlling theinovementofthe left skip up.

Letters RSU refer to the operating coil and contacts responsive theretoof a relay controlling the movement of the right skip up.

Letters Pos. refer to the positive line.

v Letters Neg. refer to the negative line.

jllifletter T refers" to time delay relays. The letters refer to theoperating coil and thecontacts responsive thereto of theundervoltage-relay.

The letters L and R refer to the operating coils and the contactsresponsive thereto for controlling the direction of rotation of the drumfor respectively raising the left skip or'the'ri'ght' skip.

U The letters FW refer to the operating coils and the contactsresponsive thereto of motor field weakening relays. Theletters SD referto the operating coils and the contacts responsive thereto of slow downrelays. I

' 'The letters CTS refer to manualjswitches for selecting anyone of sixcombinations'of elements for altenative modes of operation.

The letters LS and Rsirefer. tojmecha'nical switches closed in responseto movements of the winding 'drum. These' are termed limit switches?Though in the drawing the switches LS RS are represented as being on onedrum, actually in practice it is preferred to mount them on; separatedrums; the LS switches being associa-ted. with the left skip and the RSswitches j 'i'he elementsbr the switches'LS and RS are represented byoblong boxes having their long -airesvertical. The'oblong boxes havingtheir long dimensions horizontal represent the portions of the cycle ofoperationduring which the cor tionunits I and 8. -The lowespeed sidesofsaid gear reductionunits Land 8 are connected'respectively to pinions9 and Ill, which mesh .with the .gear .I I. Said gear. H. is rigidlysecured-.fto the'drumll 2, which has secured thereto the cables l3 andlL.- Said cables l3 and 14. may..-l;\e.conr-.v nected respectively .tothe right skip and the left skip ofa blast furnace charging mechanism.-...It will be understood'that when one or bothotthe motors ..I -.2 areenergized to cause rotationpf the windingldrum' I2 in onedirection, one.lithe said cables l3 and M will be reversed. Limit W switch meansconnected to be driven in syn: chronism with the drum 12 are indicateddia: grammatically by the numeral l5.

A description of the electrical diagram in Figv provided to switch themotor armature circuits ure 2 may be prefaced by a statement of thesignificance of the numerals and letters used thereon ,as follows:Letter G refers to the generators.

Letter M refers to the motors. V v Letter R refers to contact terminalsof resistors.

responding switch elements arebridged. i

Contact's biased to'open position are indicated by j'vr'tical' parallel"lines and contacts biased 'to olosedpositionare indicated-by verticalparallel lines with'adiagonal line therethrough. 'Ingeneral}contactorsand relays are, identinee bythe characters applied totheir operatingcoilsarid the contacts thereof are differentiated byfthe addition ofsufIixes."For. example, I GF represents the operating coil .of acorresponding oontactor and the characters flGFl, IGF2 and lfGFarepresentth-econtacts of said contactor. Thenumerals I l, 12. precedingother characters referjto'iinstrumentalities associated with motor f.The numerals 21, 22 preceding other char' acters refer toinstrumentalities associated with motor zil,.,,n,

"' Referring to Figure 2, part A, a motor generatoriset illustrateddiagrammatically by the motor armature M3, the generator armatures GIand G2 (connected to be driven by said armature M3) the exciter armatureEX and the generator series field "coils marked Gen. l Ser. Fld. andGen. 2 Ser. Fld. Double throw knife switches IKSA; IKSC, 2KSA, 'ZKSC,KSD.,and KSE are as required and as tabulated in Figure 3. (to bediscussedhereinafter). A'circuitbreaker CB ispiov'ided'having two poles,one of which is con' nected between the positive terminals of the twognerator ai'matfires GI an'dGZ; the other pole The motors Nos. 1 and 2contemplated in the present invention are mill type motors, preferablyhaving approximately th same capacities. lvliil type motors haveacquired a distinct status in the art and are capable of carrying asubstantial overload over rated capacity for material periods of time.

The generators GI and G2, as contemplated in the present invention,preferably having approximately the same capacities, each having acapacity for regularly supplying the current at the voltage suitable forpowering either of the motors MI or M2, operating at rated capacity.

The armatures of motors I and 2 are indicamd by the characters MI and M2and have in their respective circuits a plurality of directionalcontacts, conventionally illustrated series field windings (marked"motor I SF and motor ZSF for motors I and 2, respectively), seriesbrake relays ISBR and ZSBR and overload relays IBL and ML. In circuitwith the armature EX of the exciter between the positive line Pos. andthe negative line Neg. are the exciter commutatin field winding Ex.Comm. F'ld. and the series field winding Ex. Ser. Fld. From the Pos.line, paralleling the exciter armature circuit, is a shunt field windingEx. Sh. Fld. in series with a suitable adjustable rheostat Ex. Sh. Fld.Rheo. Said exciter armature EX delivers current through the commutatingfield winding EX. Comm. Fld. and the series field winding Ex. Ser. F'ld.to the positive line Pos. and the negative line Neg. I

Located in the positive and negative lines are the two poles of thedouble-pole, single-throw knife switch KSB, both poles of which areprovided with fuses. Connected across the positive and negative linesimmediately beyond the fused knife switch KSB are the generator shuntfield windings Gen. I Sh. Fld. and Gen. 2 Sh. Fld. for generatorarmatures GI and G2, respectively. Double pole, double throw knifeswitches KSJ and KSK are provided so that either generator shunt fieldwinding may be cut into or out of circuit, a resistor being providedwhich may be cut into the circuit in place of either generator shuntfield winding by means of said knife switches KSJ and KSK. Connected inseries with the generator shunt field windings are the contacts ofrelays IGFI and IGFZ which serve to connect said shunt field windingsacross the positive and negative lines. Also located in series with thecontacts IGFI, the generator shunt field windings and the contact IGFZis the resistor having the taps RI, R2, R3 and R4. Contacts 2GFI, 3GFIand IGFI serve to vary the effective resistance of said resistor.

Referring now to Figure part B, a circuit is illustrated between thepositive and negative lines which includes the motor shunt field windingI Sh. Fld. and. 2 Sh. Fld, both being adapted to be connected in serieswith a suitable filed adjusting resistor having the taps R5, R6, R1, R8and R9 which. in combination with the contacts IFWI and ZFWI and theknife switches SASI and SASZ, control the effective resistance of saidresistor. Controlling the motor shunt field winding I Sh. Fld. is thedouble-pole, doublethrow knife switch KSF and controlling the motorshunt field 2 Sh. Fld. is the double-pole, doublethrow knife switch KSG.By means of these knife switches resistor having the taps RI 4, RI maybe substituted for motor No.'1 shunt field winding 6. I Sl'i. Fld, andresistor having the taps RIB and RI I may be substituted for the motorshunt field winding 2' Sh. Fld.

Next is the brake circuit connected across the positive and negativelines through the contacts EBRI and ZBRI and a current limiting resistorhaving the taps RI!) and RH. Said circuit includes the brake coil IBRKfor motor No. 1 and the brake coil ZBRK for motor No. 2, either of whichmay be switched into or out of service by means of the double-pole,double-throw knife switches KSH or KSI, respectively. By means of saiddouble-pole, double-throw knife switches, a resistor having the taps RI8and RIB may be substituted for either of the brake coils IBRK or ZBRK.

Disposed in the positive and negative lines below the brake circuitimmediately above described is a double-pole control switch indicated asCS.

The circuits across the line between the posi-' tive line Pos. and thenegative line Neg. are numbored I, 2, et cetera. Circuit I extends fromthe positive line Pos. through the stop-reset push button (biased toopen position) through the coil UV of an under-voltage relay, thenormally closed contacts iIJLl, ZGLI, FL! and SCI to the negative lineNeg. The stop-reset push button is provided with two movable contactsadapted to alternatively bridge the fixed contacts aa or bb. Saidcontacts b-b are arranged in parallel with the contacts aa. Located inthe positive line Pos. between the connections to contacts d-a. andcontacts bb are the contacts UV! responsive to the under-voltage relaycoil UV. Said contacts UVI are biased to open position.

Circuit 2 extends from the positive line Pos. through the single polepush button switch LSUPB (biased to open position), through the relaycoil LSU, thence to the limit switch contacts LS3 and to the negativeline Neg.

Circuit 3 extends from the positive line Pos. through the push buttonswitch RSU-PB (biased to open position) through the relay coil RSU,thence through the limit switch contacts RS3 to the negative line Neg.

Circuit 4 extends from the positive line Pos. through the contacts LSUI,ISBRI and 2SBBRI, thence through the operating coil IBR to the negativeline Neg. Said contacts LSUI, ISBRI and. ZSBRI are biased to openposition. Across the open contacts ISBRi are contacts A and B and acrossthe open contacts 2SBRI are contacts B and. C. Said contacts A, B and Care connections of a switch CTSI. Said contacts A, B and C are used toshunt out the normally open contacts ISBRI or ZSBRI as required undercertain operating conditions.

Circuit 5 extends from the positive line Pos. through the contacts RSUI(biased to open position) and the contacts lBRZ (biased to openposition) through the relay coil 2BR to the negative line Neg. Thenormally open contacts IBR2 are bridged across the two pairs of contactsI SBRI and ZSBRI.

Circuit 6 extends from the positive line Pos. through the contacts IBR3(biased to closed position) and through the timer relay coil IT to thenegative line Neg.

Circuit I extends from the positive line Pos. to the contacts ITI(biased to open position) through the relay coil 3BR to the negativeline Neg.

Circuit 8 extends from the positive line Pos. through the contact LSU2(biased to open position) through the contacts CTS2, contactor coils HLand IZL, in parallel with each other, to the negative lin Neg. Branchingfrom'the circuit 8 at a point beyond the contacts LSU2 is a branchcircuit 8a which leads through the contacts C'IS3and coils 21L and 22L,in parallel with each-other, to the negative line Neg. Y

Circuit 9 is analogous to circuit 8 and extends from the positive linePos. through the contacts RSU2 (biased to open position) through thecontacts'CTS4 and coils LR and I2R, in parallel with each other, to thenegative line Neg. Branching from the circuit 9 at a point beyond thecontacts RSUZ is the branch circuit 9a which leads through the contactsCTS5 and coils 2IR and 22R, in parallel with each other, to the negativeline Neg. *Circuit l extends from the positive line Pos. through thecontacts LSU3 (biased to open posi tion) through the contacts IFW2(biased to open position), in parallel with which are the contacts IGF3(biased to open position), thence through the contacts IT2 (biased toclosed position) and through the relay coil IGF to the negative lineNeg.

- Circuit ll extends from the positive line Pos. through the contactsRSU3 (biased to open position), through the contacts ZSDI (biased toopen position), through the contacts 2T! (biased to closed position),through the contacts IGF l (biased to open position) and through therelay coil ZGF to the negative line Neg.

Circuit I2 is a branch of circuit II and extends from a point beyond thecontacts RSU3 through the contacts lSD l (biased to open position), thecontacts 2GF3 (biased to open position), the contacts 3Tl (biased toclosed position) and the relay coil 3GP to the negative line Neg.Shunting the normally open contacts lSD l is a circuit including thecontacts 3GF2 (biased to open position) and the contacts 9T! (biased toopen position);

Circuit l3 extends from the point of intersectionof circuit l2 withcircuit H through the contacts 8TI (biased to open position) throughcontacts 3GF3' (biased to open position) through contacts 4Tl (biased toclosed position) and through the relay coil 4GP to the negative lineNeg.

Circuit'M extends from the positive-line Pos. through the contacts LSUQ(biased to open position), through the contacts 5Tl (biased to openposition) and through the relay coils IFW and GT, in parallel with eachother, to the negative line Neg. Disposed in parallel relationship withthe contacts 5T! are the contacts ITI (biased to open position).

Circuit I5 extends from the positive bus Pos. through the contacts RSUA(biased to open position) through the contacts 6Tl (biased to openposition), and the relay coil ZFW to the negative line Neg. Shunting thecontacts ETI are the contacts I SDI (biased to closed position). Alsoshunting the contacts 6T! are the contacts 6TS6 (biased to openposition). Contacts LSU4 and RSU4 are connected in parallel with eachother. Circuit l6 extends from the positive line Pos. through the relaycoil ISD through the contacts LSU5 (biased to open position) and thelimit switchcontacts LSI to the negative line Neg. In parallel with thecontacts LSU5 and the limit switch contacts LSI is a circuit includingthe contacts RSU5 (biased to open position) and the limit switchcontacts RSI.

Circuit [1 extends from the positive line Pos.

.8: Y through the relay coil 2SD through the contacts LSUG and thelimit, switch contacts LS2 to the negative line Neg. In parallel withthecontacts LSUG and the contacts LS2 is a circuit including the contactsRSU B (biased to open position) and the limit switch contacts RS2.

, Circuit l8 extends from the positive line Pos. through the contacts|GF5 (biased to closed position) and the relay coil 2T to the negativeline Neg.

Circuit 19 extends from the positive line Pos.

through the contacts 2GF4 (biased to closed position) and the relay coil3T to the negative line Neg.

Circuit 20 extends from the positive line Pos. through the contacts 3GF3(biased to closed position) and the relay coil 4T to the negative lineNeg.

Circuit 2| extends from the positive line .Pos. throughthe contacts4GF2and the relay coil 5T to the negative line Neg.

Circuit 22 extends from the positive bus Pos. through the contacts ISDZ(biased to open position) and the relay coil IT to the negative lineNeg. I

Circuit 23 extends from the positive line Pos. through the contacts IFW3(biased to closed position) andthe relay coil 8T to the negative lineNeg. Shu'ntin'gthe normally closed contact IFW3 is the contact |SD3(biased to open position).

Circuit 24 extends from the positive line Pos. through the contacts 8T2(biased to open position) and the relay coil 9T to the negative line.

MODE OF OPERATION By means of theswitches IKSA, 2KSA, IKSC, 2KSC, KSEIKSD and the circuit breaker CB, the two motors having armatures MI andM2 and the two generators havingthe armatures GI and G2 may be connectedin various combinations for various functions as scheduled on Figures 3and 4. These several combinations will be explained individually asfollows:

Nos. 1 and 2 generators in parallel serving both motors in parallel To,accomplish, this combination, switches IKSC, .2KSC, KSD and KSE areclosed in the up .position. ,The circuit breaker C13 is closed andswitches IKSA and ZKSA are closed down. Under such conditions the.motors and generators are in parallel and. thegenerator series fieldwindings are crossed to insure load equalization between the generators.

Overload relay protection is afforded by overload relay IOL in the No. 1motor armature circuit and the overload relay 20L in the No. 2 motorarmature circuit.

Series brake relays ISBR and ZSBR, in the motor armature circuitscontrol the release of the brakes under the influence of the motorseries current.

Direction of the rotation of the motors is controlled by the directionalcontact or contacts IIL, HR, I2L and HR in the No. 1 motor circuit and2|L, ZIR, 22L and 22R in the No. 2 motor circuit. These contacts arecontrolled by the respective directional relays heretofore shown, beingcontrolled by the directional relays LSU and RSU, which, in turn, arecontrolled by the directional push buttons LSU-PB and RSUPB according tothe simplified diagram of Figure 2, but which might be controlled by anyconvenient combination of equipment.

.Speed control is initially provided by the regu- 9 lation of thegenerator voltage. This is accomplished by operating the relays ZGF, 3GFand 4GB. When successively closed, these relays build up the generatorvoltage in steps. It may be assumed that the exciter voltage has beenregulated to a desired value (usually 230 volts D. C.) by means of theexciter field rheostat Ex. Sh. Fld. Rheo. Likewise control switch KSBmust be closed providing energization (usually at 230 volts) of thegenerator shunt field winding, the motor shunt field windings, thebrakes,

and the control devices.

The generator shunt field windings are connected in series across the230 volt circuit between the positive line Pos. and the negative line,

Neg, being in series with the contacts IGFI and I GI -2 and the voltageadjusting resistor having the taps RI, R2, R3 and R4, connections towhich are controlled by the contacts 2GP, 3GP

and 4G1? Control of this resistor affects the voltage applied to themotors Ml, M2.

The series field windings of the No. 1 and 2 generators are controlledby means of the switches KSD and KSE. When the generators are operatedin parallel the switches are both turned to the up positions connectingthe series field winding of No. 1 generator in the No. 2 armaturegenerator circuit and the series field winding of the No. 2 generator inthe No. 1 generator armature circuit, thus accomplishing a balancedloading of the two generators.

The two-pole circuit breaker GB is provided to protect the generatorsfrom circulating current when they are operated in parallel. In practicesuitable trip coils, not illustrated, are provided for operating thecircuit breaker CB.

One generator serving both motors Either generator may be cut out ofcircuit as desired by the proper manipulation of switches IKSA, ZKSA,KSD, KSE, IKSC and ZKSC in the armature circuit of the generators. Whencutting out one generator it is desirable to cut out the shunt fieldwinding of that generator. This is done by the selective manipulation ofswitches KSJ and KSK. When thrown up, switch KSJ connects the shuntfield winding of generator No. 1 into circuit. When switch KSJ is throwndown, the resistor having the taps R12 and R15 is substituted for thefield winding Gen. l Sh. Fld. Similarly when switch KSK is thrown up,the generator shunt field winding is connected in circuit and when saidswitch KSK is thrown down, the resistor having the taps Rl2, Rl3 issubstituted for said winding. When the generators are operatedindividually, the generator series field windings are connected directlyin their respective armature circuits by throwing switches KSD and K815to their down positions.

Various combinations of motors and generators According to the presentinvention, motor No. 1 and motor No. 2 may be operated separately or inparallel or in series as conditions dictate, the choice of operationbeing controlled by the choice of switch positions as indicated inFigures 3 and 4. Position No. 1 indicates conditions under which motorsNo. 1 and No. 2 are operated in parallel, being fed by No. 1 and No. 2generators in parallel. Position No. 2 indicates conditions under whichmotor No. 1 is fed from generator No. 1 and motor No. 2 is fed fromgenerator No. 2. Position 3 indicates conditions under which No. 1generator feeds both No.1

10 i and No. 2 motors connected in series. Position No. 4 indicatesconditions under which No. 2 generator feeds motor No. 1 and motor No. 2in series. Position No. 5 indicates conditions under which No. 1generator and No. 2 generator are connected in parallel, feeding No. 1motor only. Position No. 6 indicates conditions under which No. 1 andNo. 2 generators in parallel feed No. 2 motor.

Single motor operation I During periods of single motor operation it isdesirable to cut out the shunt field winding of the motor not in use.This is accomplished by means of the motor field switches KSF and KSG(Figure 2, part B). When thrown into the up position, switch KSF willconnect No. 1 motor shunt field winding in circuit. When said switch KSFis thrown down a replacement resistor having the taps RM, Rl5 will beconnected in place of No. 1 motor shunt field winding, l Sh. Fld. Whenswitch KSG is thrown to the up position, No. 2 motor shunt field windingis connected in circuit. When said switch KSG is thrown down, areplacement resistor having the taps RIB, Rl'l is connected in thecircuit.

In the shunt field circuit of the motors is a resistor having the tapsR5, R6, R1, R8 and R9,

having one of its terminals connected to the positive line Pos. and theother of its terminals connected to switch KSF, the other side of switchKSF being connected to one side of the switch KSG, the other side ofsaid switch KSG being connected to the negative line Neg. This multitapresistor having the taps R5, R6, R1, R8 and R5, being in series with theshunt field windings l Sh. Fld. and 2 Sh. F1d., is a motor speedadjusting resistor. The speed variation may be accomplished by operationof the contacts IFWI and 2FWI. These contacts are adapted to shunt outportions of said resistor. In addition to the contacts I FWI and ZFWIare two speed adjusting switches SASI and SASZ which may be opened orclosed to adjust the portion of the resistor affected by operation ofthe contact 2FWI, thus predetermining the top speed at which the motoror motors will operate.

The operating coils for the two brakes are shown diagrammatically inFigure 2, part B, said coils being connected in series across thecircuit from the positive line Pos. to the negative line Neg. in serieswith the contacts IBRI and the contacts ZBRI and a resistor having thetaps RIB, RI

The brake operating the coils IBRK and ZBRK are connected to ordisconnected from the circuit by means of the knife switches KSH andKSI. When switch KSH is thrown up, it connects the operating coil IBRKin circuit and when thrown down will connect in circuit a replacementresistor having the terminals Rl8, Rl9.

Knife switch KSi when thrown up will connect the operating coil of No. 2brake and when thrown down will substitute the replacement re=- sistorhaving the terminals RIB, Bill. The resistor having the terminals RIO,RH serves to limit the current in the brake coils to a safe value.

Continuing with Figure 2', part B, the plurality of circuits comprisingthe control of the generators, motors and the brakes and the otherelements of the hoist control will now be discussed.

Referring to circuit 1 the stop reset push button is a two-element pushbutton having top contacts a-a and bottom contacts bb. One of thecontacts aa is connected to the positive positive line Pos. on the otherside' of-"saidcontacts UVI. The othercontacts a and b are connectedtogether'ai'idtdthUVYlay coil. From the other side oftheUY relaycoil-the circuit continues through the normally closed contacts IOLI,ZEJLI, FL! and SCI to the negative line Neg. The contacts UVI areactuated by the coil UV just referred to; "1

Should the continuityof the UV coilcircuit be interruptedby*thebpeningof one of the sets of contacts in series'witl lthe'c'oil UV, it willbecome de-ener gizedand remain so until the contacts are again closed.

To reclose the contacts UVI following the opening of any of the contactsreferred to, it is necessary to push the stop reset button to open thecontacts b--b and close the contacts a a. This re-establishes UV coilcircuit resulting in the closure of contacts UVI. The push stop resetbutton may then be released. Contacts b-b control. The limit switchcontacts LS! are part of a limit switch mechanism driven insynchronization with the shaft of the winding drum 12. I

Circuit 3 is analogous to circuit 2, the limit switch contacts RSI beinganother part of the limit switch mechanism driven in synchronizationwith the drum I2.

Referring to circuits 4 and 5 (Figure 2, part B) the contacts LSU! areresponsive to energization of the coil LSU and the contacts RSUI areresponsive toenergization of the coil RSU in circuit 3. Therefore theclosure of either of the contacts LSU! or RSUI will result in theactuation of the brake relay coils IBR and 2BR provided the remainder ofthe elements of the circuit are properly set up'to function. The closureof the normally open contacts LSU! or RSUI is a function of theoperation of the relay coils LSU or RSU which, in turn, are responsiveto the push buttons LSU-PB or RSU-PB, respectively.

The normally open contacts ISBRI and ZSBRI are responsive to theirrespectiv relay coils ISBR and ZSBR, the former being in the armaturecircuit of motor No. 1 and the latter being in the armature circuit ofmotor No. 2 (Figure 2, part A).

Thus, when the motors are energized, the series brake relay contactswill close when sufilcient current isbuilt up in the armature circuitsto cause them to function. This insures a current of proper magnitude toprovide torque enough for the motors to handle the load before releaseof the brakes, for as soon as relay contacts ISBR and 2SBR close, thenormally opened contacts LSBRI and ZSBRI in th [BR and 2BR circuitsclose. When either contacts LSU! or contacts RSUI are closed, circuitwill be completed through the coils IBR and 2BR, causing them to closecontacts iBR2 in the brake relay circuit (circuit 5), shunting thecontacts ISBRI and ZSBRI. Norm-ally closed contacts IBR3 are in the ITtimer relay circuit (circuit 6), and when operation.

that circuit is open, the IT timer starts its timing Simultaneously withthe closing of contacts LSU-I or RSUI, asthe case may be, severalcontactsassociated with the coils LSU or RSU close. Therefore contacts'LSUZ, LSU3, LSU4, LSU5 and LSU6 or contacts RSU2, RSU3;RSU4, RSUE andRSUB are also closed:

Referring to circuit v8, circuit, is completed from the positive linePos. through contacts LSUZ. In case of LSUop'eration; circuit wouldcontinue through the contacts LSU2 "to-points of .the controltransfer-switcl1CTS2 and CTS3. During two-motor operation, both CTSZ andCTS3 will be closed. For No. 1 motor operation only CTSZ will be closedand for No. 2 motor operation only CTS3 relay' operated, contacts LSU2will complete a circuit from the positive line Pos. through contactsCTS2 through the directional contactor coils l IL and IZL to thenegative line Neg, closing the directional contactors l IL and IZL.

In like manner, the directional contactor coils 21L and 22L will beoperative through contacts are closed in response to the energization ofeither of the directional relays LSU or RSU at the start of operation ofthe skip hoist. Likewise the normally closed contacts [T2 are closedwhen the relay "coil IBR (circuit 5) is energized to open its normallyclosed contacts IBR3 in the IT relay circuit, thereby allowing contactsIT2 to close, completing circuit through the coil IGF and causing thatrelay to close its contacts IGFI,

- "IGFZ, 'IGF3 and lGFE and causing the normally closed contacts IGF5 toopen.

Contacts IGFI and IGF2 close the generator field circuit from thepositive line Pos. through the adjusting resistor (having the taps RI,R2,

' R3 and R4) and through the generator shunt fields Gen. l Sh. Fld. andGen. 2 Sh. Fld. to the negative line Neg. (Figure 2, part A.)

Contacts IGFEB form a holding circuit in the IGF relay circuit, shuntingcontacts IFWZ (Fig- 'ure 2, part B) which will open prior to the timerequired for IGF relay to be deenergized.

Referring to circuits ll, 12 and I3, contacts IGF4 form part of aninterlock in the 2GF relay coil circuit to prevent it from'closingbefore the lGF' relay is energized. I

The normally closed contacts IGF5 form part of the 2T timer relay coilcircuit. The opening of contacts IGF5 starts the ET relay to time, the

completion of which results in the de-energization of the operating coil2T, causing contacts 2T! to close after contacts Z-SDI and'IGFA hadclosed.

In like manner the contacts responsive to the generator voltage controlrelay coils 3GF (circuit 7 i2) and 4GP (circuit l3) are closed insequence,

resulting from the closure of contacts ZGF3, followed by the opening ofcontacts 2GF4 in the circult of timer coil 3T, causing the delayedclosing of contacts -3TI in the SGF coil circuit.

13 closed by reason of the energization of the relay coil ST.

The procedure up to this point has completed the generator voltagebuild-up to its maximum and the next step is motor field weakening.

Proceeding now to a discussion of circuit l4, motor field weakening isaccomplished in two steps, through the operation of the motor fieldweakening relays IFW and 2FW. Operation of the relays IFW and ZFW isinitiated by closure of contacts LSU4 or RSU4 which act initially onrelay I'FW, the functioning of relay IFW causing the actuation of therelay 2'FW as follows:

When relay 4GP has operated, the 4GF2 normally closed contacts in the STtimer circuit open, causing the contacts 5T! of relay timer 5T to openafter a time interval. In parallel with the relay coil IFW circuit is acircuit including the timer relay coil 6T which is also de-energizedwhen contacts 5T| open. In parallel with contacts 5T! are contacts lTlwhich respond to the time delay relay IT, the energization of which isresponsive to contacts ISD2 which, in turn, are responsive to the relayISD which closes when the contacts UVI are closed.

The relay coil ZFW is de-energized upon the opening of contacts 6T!which opening occurs when the time delay contacts 5TI open. Thus thecontacts lFWl across the taps R5 and R6 and the contacts ZFWI across thetaps R6 to R9 of the speed adjusting resistor in series with the motorshunt field windings are opened in sequence, accelerating the motors tomaximum speed after the generator voltage had previously been built upto a maximum.

With the hoist running at maximum speed it continues to operate in thatmanner until the mechanically operated limit switch LS or R8. drivenfrom the hoist drum, has moved sufficiently far to cause the opening ofswitches LSI or RSI (depending respectively upon whether the left skipor the right ship is ascending) at whicn point the circuit of the relaycoil ISD is broken which circuit had been held closed while the contactsLSU5 or RSU5 were closed (circuit 16).

When the relay coil I'SD is de-energized, its contacts ISDI close andits contacts ISDZ, ISD3 and ISDA all open. Closing of the contacts ISDlin circuit with the relay coil 2FW causes the energization of that relaycoil closing the contacts 2FWI across the motor shunt field adjustingresistor having the taps R6 to R9, causing the motors to slow down. Whenthe contacts I SD2 open, it causes the de-energization of the timer coil1T, causing its contacts lTl to close after a predetermined timeinterval. This re ults in the energization of the coil IFW, causing thecontacts I'FWI to close, shunting out the remainder of the motor shuntfield resistor between taps R5 and.

R6, further slowing the motors. Contacts ISD3 having opened and contactsIFW3 being already opened, the time relay coil ST is ole-energized andaccordingly after the lapse of a predetermined time interval, thecontacts BTI and GT2 open. The opening of contacts BTI breaks thecircuit of the relay coil AGF allowing the contacts AGFI to open,inserting into circuit that part of the generator shunt field resistorbetween contacts R3 and R4, lowering the generator voltage, thus furtherreducing the motor speed.

The opening of contacts 8T2 results in the deenergization of the timedelay relay coil 9T whereby, after the lapse of a p edetermined timeinterval, the timer relay contacts STI will open (circuit I2). I

' contacts LS2 or RS2 to open, thereby breaking circuit of the relaycoil ZSD (circuit 17).

When the relay coil ZSD is de-energized, its contacts ZSDI (circuit ll)open, thereby de-energizing the relay coil ZGF. Contact ZGFI, in thegenerator field circuit, opens, inserting into that circuit, that partof the resistor between taps RI and R2, lowering the generator voltageto its lowest value.

The hoist continues to operate at reduced speed until the mechanicallimit switch has traveled to a point where the switches LS3 or RS3 areopen, thereby open circuiting the relay coil LSU or RSU, depending uponwhether the left skip or the right skip is ascending.

When the coil LSU or the coil RSU is open circuited, all the contactscontrolled by these coils are open. The opening of the contacts LSU3 orRSUS (depending upon the direction of operation) results in thede-energization of the relay coil IGF, allowing its correspondingcontacts to open, completely de-energizing the generators. setting thebrakes and stopping the hoist.

The foregoing discussion has referred to functions as they occur duringoperation as governed by position CTS No. 1 (Figures 3 and 4). For CTSposition No. 2 operation of the hoist is in many respects the same asfor CTS position No. 1, but the circuit breaker CB under conditions ofposition No. 2 is open; the generator series field windings areconnected in their respective armature circuits instead of beingcross-connected; and for CTS position No. 2 switches KSD and KSE areclosed down. Otherwise all devices function as for position No. 1.

CTS position No. 3 refers to a circuit which permits No. 1 and No. 2motors to be used in series. Under these conditions with only generatorNo. 1 in service, the motors will receive equal torque as the currentfrom the generator passes through both motors. Thi insures equal gearloading and equal motor loading.

For CTS position No. 4 operation the connections established are similarto those for position No. 3 operation except that the No. 2 generator isused instead of No. 1, the motors bein in series.

Condition under CTS positions No. 5 and 6 are similar in that in eachinstance the generators are in parallel. Under position No. 5 only No. 1motor is used and under position No. 6 only No. 2 motor is used. Underthese operating conditions it is possible to take advantage of themarginal capacity of the mill type motors being used. This permitenhanced single motor operation without a corresponding increase ingenerator size.

Though a preferred embodiment of the present invention has beendescribed in detail, many modifications will occur to those skilled inthe art. It is intended to cover all such modifications that fall withinthe scope of the appended claims.

It is claimed:

1. In combination, a member to be driven, a

m mber.

po s pp yin relationship-With a d. mot rs. i

series and control m mr po ive mmovement of said member to bedflverrionmodifying, the circuits or said ,motors andv generators tocause, a re cribed cycle of, movement of said In combinatiomfla member,to be driven, a first motor, a first generator suitablefor supplyingsaid motor, a second motor, a second generator suitable \for supplyingsaid second .motor, said motors being mechanically connected to saidmember, switch, means for alternatively connecting said generatorsinparallel tosupply said ,two motors in parallel or for connecting eitherof said generators to said two motors connected in series and controlmeans responsive to movement of said member to be driven for modifyingthe circuitsof said motors and generators to causea prescribed cycle ofmovement of said member. r 3. In combination, a member to be driven, afirst motor,- a first generator suitable for supplying said motor, a;,second motor, a second generator suitable for supplying said secondmotor, said motors being or -approximately the same capacity, saidmotors bein mechanically connected to said membenswitch means forconnecting said two motors independently to their respective generatorsor for connecting one of said generators with the two motors connectedin series and control means responsive to movement of said member to bedriven for modifying the circuits of said motors and generators to causea prescribed cycle of rnovement of said member- 1""! 4. In combination,a member to ,be driven, a first motor, a first generator suitable forsupplying said motor, a second motor, a second generator suitable forsupplying said second motor, said motors being mechanically connected tosaid member, switch means for connecting said two motors independentlyto their respective generators or for connecting one of said generatorswith the two motors connected in series and control means responsive tomovement of said member to be driven for modifying the circuits of saidmotors and generators to cause a prescribed cycle of movement of saidmember.-

5. In combination, a member to be driven, a first motor, a firstgenerator suitable for supplying said mot0r, -a second motor, a secondgenerator suitable for supplying said second motor, said motors beingmechanically connected to said member, switch means for connectin saidtwo motors and said two generators in parallel relationship oralternativelyconnectingone of said generators with the two -motors"connected in series and control mean responsive to move- ,ment of saidmember to, be driven for. modifying the circuits of said motors andgenerators to cause a prescribedfcycle of movement of said member.

6. In combination, a, member .to be driven, a

'thetyvo motors connected in series and control means responsive tomovement of said member o b d iv n, f r, mod in t e. r ui s i s moto sra s ne at sutq a -S a p sc bed Cycle of oy me t of sai bers.

, C oiqomb nat on a m m e w d ive a first motor, a first generatorsuitable for supplyingsaid motor, a second motona second genera r suitae for umm n a d Second mot r said motors being mechanically connected tosaid member, switch "mean for connecting one d mqt rsi ise en ors, cv neiedsin parallel or forconnecting one of said generators to said twomotors connected in series and controlmeans responsive to movementofsaid member to be driven for modifying the circuits or said motors andgenerators to cause a prescribed cycle of movement of said member.

8. In combination, amember to be driven a first motor, a first generatorsuitable for supplying i m r n ec nd t a 5'39111 erator suitable forsupplying said second motor, said motor being mechanically connected tosaid member and switch-means for alternatively connecting-saidgenerators to said motors individuallyor for connecting said generatorin parallel to either oneof said motors, or for con- 1 1ecting one ofsaid generators to said motors in series, and'oontrol means responsiveto movement of saidmemb er to be driven for modifying the; circuits ofsaid motors and generators to Cause apreseribed, @y p movement ofsaid 9,In combination, a mjember to be driven, a first motor, a first generatorsuitable forsupplying said motor, a second motor, a second generatorsuitable for supplying said second motor,- said motors beingmechanically eonnected to said member, switch means foralter na i r qenti i eae s to e arately powersupplying relationshipwith its ,res e t vaqiot Q i rb r i qii a .generators 'tosaid two motors spewin in series,and control meansresponsive to movementof said member to be driven formodifying the circuits o fisa id motors la ndi generators to cause a;prescribed cyclof movement of saidmember.

10. 11; combination a member to be driven, a rs t ge l ierator suitablefor-supplying' said rho or, a second: motor; asecond generator suitablefor supplying said second rap or, said m0tors being" mechanically" connected to said member, switch means for connect n as We m t s s di a s,c r nected in parallel or tor connecting one of said oto s-rte aid eerat n te in were Icrefo r nneeiins on S d at r tesa two motorsconnected in series, andcontrol means re o sive move e i f' S me e 0driven for: modifying-the circuits of said motors and generators tocause aprescribed cyclepof movement of said member c ,li In combinationamember tobe driven, a first motor, .a first, generator suitable iorsupplying said motor, a second motor, a second seg raio i s table, f sup yin 1 said s ond motor, said motor being mechanicallyc'onnected 17 tosaid member, said generators having armatures and series field windings,switch means for connecting said two motors to said generator armaturesconnected in parallel and for crossconnecting said generator seriesfield windings, or for connecting said two motors separately to theirrespective generators and for connecting the series field windings ofsaid generators each in series with its respective armature, and controlmeans responsive to movement of said member to be driven for modifyingthe circuits of said motors and generators to cause a prescribed cycleof movement of said member.

12. In a skip hoist assembly having at least one skip, a skip hoistdrive assembly comprising in combination, a member to be driven whichmember in turn operates said skip, a first motor, a first generatorsuitable for supplying said motor, a second motor, each of said motorshaving a shunt field winding, a, second generator suitable for supplyingsaid second motor, said motors being mechanically connected to saidmember for drivin said member, said generators having armatures, seriesfield windings and shunt field windings, exciting means for exciting theshunt field windings of said motors and generators, switch means forconnecting said two motors in parallel to said generator armaturesconnected in parallel wherein the series field windings of eachgenerator is connected in series with the armature of the othergenerator, or for connectin said two motors separately to theirrespective generators wherein the series field windings of each of saidgenerators is connected in series with its respective armature or forconnecting one of said motors to said generator armatures connected inparallel wherein the series field winding of each of said generators isconnected in series with its respective armature, or for connecting oneof said generator armatures to said motors connected in series whereinthe series field winding of each of said generators is connected inseries with it respective armature, and control means responsive to theoperation of said skip for modifying the circuits between said excitingmeans and the shunt field windings of either or both of said motors andgenerators to cause a prescribed cycle of operation of said skip.

13. The skip hoist assembly of claim 12, said motor and generator shuntfield windings and said exciting means having variable resistance meansconnected therebetween, and said control means comprisin interlockingrelays, timers, contactors, control transfer switch means set inpredetermined positions according to the setting of said switch means, amanual control switch means and limit switch means responsive to theoperation of said skip; said limit switch means cooperating with saidinterlocking relays, timers, contactors, control transfer switch meansand said manual control switch means to cause completion or opening ofcircuits between said exciting means and said generator shunt fieldwinding, and variation of the resistance of said variable resistancemeans connected between said exciting mean and said motor and generatorshunt field windings, to cause a prescribed cycle of operation of saidskip upon the manual operation of said manual control switch.

GORDON FOX.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,390,624 Lamme Sept. 13, 19211,781,792 Rodman Nov. 18, 1930 2,433,786 Ridgway Dec. 30, 194;?

